This invention relates to lasers and more particularly to Q-switches therefor.
A laser typically comprises a laser medium such as a solid state crystal rod, which is positioned within a resonant cavity formed by a pair of mirrors, one of which is totally reflecting at a desired wavelength of the laser, and the other being partially transmissive at the desired wavelength. A pumping source, such as a zenon flash lamp is employed to raise the atoms in the laser medium from the ground state to an excited state. Lasers often employ a Q-switch therein to suppress the laser action until a large population inversion of excited state atoms in the laser rod has been achieved. Mechanical or electro-optical Q-switches, such as Kerr cells, are frequently employed; however, they are relatively complex and expensive both in terms of the number of component parts and in the manufacturing thereof.
To avoid the expense and complexity of the mechanical or electro-optical Q-switches, the passive Q-switch has been employed. Passive Q-switches can be merely a dye disposed within a liquid or plastic medium. For many applications these conventional passive Q-switches are quite satisfactory. However, the demands have grown for passive Q-switches in lasers which operate at relatively high repetition rates. The peak power generated from such high repetition rate lasers is generally not much different from those of very low repetition rate lasers. However, the average power applied to the passive Q-switch is sufficiently high to cause deformation thereof or even melting.